I wrote a very short book on Getting Things Done for
hackers, which I also put up for sale
on Amazon as a Kindle book, in addition to allowing people to get it
for free from my website. As expected, it didn't sell much, perhaps a
few dozen copies in total, but I got a small kick out of having a book
for sale.

However, Amazon now wants me to set up some kind of US tax account,
which is all fine and good and legal and appropriate, but it's not
worth my time to do that. I've removed the book from Amazon, to
keep my life simple.

It continues to be available on its own website, including in a Kindle
format. For free. Under a CC-BY-SA 3.0 license. Since I see the
download statistics for it, I know how many people download it. The
PDF form is most popular, as it happens. All good.